Captive screws used on sheet metal plates, most often releaseable panels, provide a means for securing the panels while providing screw retention to eliminate loose hardware. These devices avoid extra parts and conveniently hold the screws in a resiliently retracted position, yet maintain them attached to the sheet metal panel. The fastener is typically attached to the panel by a screw-surrounding barrel, which is affixed either by press-fit or a rivet-type engagement. The axial movement of the screw is restricted relative to the barrel, and a spring interposed beneath the head of the screw and the end face of the barrel maintains the screw in a retracted position. These screw assemblies are often called "panel fasteners".
The closest prior art of which the applicant is aware includes U.S. Pat. No. 3,465,803 issued to R. B. Ernest et al, and U.S. Pat. No. 3,346,032 issued to B. Gulistan. The Ernest et al panel fastener provides a construction by which the captive screw assembly may be press-fit into the sheet as a unit. The Gulistan captive screw includes a telescoping sleeve which extends from the end of the barrel and surrounds the spring and head of the screw while also providing axial screw retention. The sleeve becomes affixed to the screw head during assembly and, therefore, aids rather than deters manual actuation.
While the panel fasteners of the prior art provide their intended convenience, they are subject to tampering. The screw heads are left exposed and may be easily turned manually. There is therefore a need in the art for a captive panel fastener having all the attributes of the prior art which may be easily applied, but be resistant to manual tampering.